Wet etching is a processing means commonly used in the micro-nano processing. Chemical reagents are adopted in the wet etching to etch or dissolve the material to be processed so as to remove the materials. The wet etching rate is associated with the reaction type and is also highly susceptible to the reaction temperature. The wet etching can be performed in the case where a reagent capable of etching and dissolving the material to be processed is available. Therefore, the method has been widely applied in the processing of micro-nano structures, fabrication of printed circuit boards, display devices and integrated circuits.
However, certain limitations still exist in the wet etching. For example, when a single crystal silicon is etched by a typical TMAH solution or KOH solution, the etching direction of <100> is presented as 54.7° on the surface of the workpiece, making it difficult to obtain the smooth vertical vias or grooves. In addition, micro vias and grooves with different sizes cannot be processed on the same workpiece. Therefore, it is urgent to propose a method for synchronous wet etching processing of differential microstructures to extend the application range of the wet etching processing.